Bernard Gorowitz

Direct W–Ti contacts to silicon

We have studied the contact resistance in a metallization system that employs a direct contact between a tungsten–titanium alloy and shallow junctions in silicon. The values obtained in the present study are all within acceptable limits (<100 Ω μm2) for very large scale integration applications. The metal–silicon system has been subjected to moderate heat treatments, similar to those required in processing two‐level metallization schemes. No detrimental effects on the electrical properties of these contacts have been observed.

Plasma-Enhanced Chemical Vapor Deposition of Dielectrics

Publisher Summary This chapter discusses plasma-enhanced chemical vapor deposition (PECVD) of dielectrics. Chemically reactive, low-pressure glow discharge plasmas have been used to form a number of coating materials employed in microelectronics and other applications. The key advantage of plasma-assisted reactions is that they can occur at temperatures that are usually considerably lower than are possible with thermal reactions alone. As a result, it is possible to deposit or grow films on substrates that might not have the thermal stability to accept such coatings. It has been shown that PECVD reactions typically produce nonstoichiometric films that may or may not be advantageous in terms of physical and/or chemical properties, depending on the applications contemplated. The lower deposition temperatures for PECVD dielectric films have, thus, far been the major driving forces for their use.

Methods of Metal Patterning and Etching

Publisher Summary This chapter describes the methods of metal patterning and etching. Photolithography equipment and processes are available for use in the patterning of metallizations suitable for very-large-scale-integration applications where the critical dimensions are in excess of about 1.0 μ m. Improvements in equipment, photoresist materials, and the use of multiple layers and contrast enhancement materials may push the lower limits of optical lithography to the 0.5 μ m or lower. At the same time, electron beam and X-ray lithography are being improved with the goal of implementing submicron processes on a manufacturing scale. Dry etch techniques for pattern replication also have demonstrated capabilities in the 1.0 μ m range. Decreasing geometries and increasing wafer sizes, however, represent a combination that most likely requires the abandonment of batch etch systems in favor of single-wafer systems. Etch rate improvements, as well as more accurate and more responsive endpoint detection and control, and greater selectivity to both resist and substrate are important factors in etch equipment and process development.

Chapter 10 - Reactive Ion Etching

Publisher Summary This chapter discusses reactive ion etching. The radicals and neutrals participate in chemical reactions on the film surface to produce volatile species or their precursors, while positive ions are accelerated across the plasma sheath in the inter-electrode space and bombard wafer surfaces on the cathode to initiate or complete the volatilization process and accelerate material removal. This admittedly cursory description is in itself sufficient to justify the use of synonyms for reactive ion etching, such as reactive sputter etching, ion-assisted chemical etching, and chemical-assisted sputtering. The term reactive ion etching (RIE) is used to describe any or all of these processes. RIE has been demonstrated to be an effective means of accurately and selectively replicating feature geometries in sizes that extend down to the sub-micrometer range. The practical lower limits of process capabilities have not been reached, primarily because of the inability to resolve the desired small geometries by various lithographic techniques.